Electrostatic operation device

ABSTRACT

An electrostatic operation device in which a variation in the amount of electric charges accumulated in an electret film caused by physical impact can be suppressed. The electrostatic operation device (electrostatic induction power generating device ( 1 )) comprises movable electrodes ( 8 ), an electret film ( 5 ) so formed as to face the movable electrodes ( 8 ) at a space therebetween, and a stopper ( 401   b ) for suppressing the approach of the movable electrodes ( 8 ) to the electret film ( 5 ) within a predetermined space.

TECHNICAL FIELD

The present invention relates to an electrostatic operation device, andmore particularly, it relates to an electrostatic operation devicecomprising an electret film.

BACKGROUND ART

Japanese National Patent Publication Gazette No. 2005-529574 disclosesan electrostatic operation device (electrostatic induction powergenerating device) comprising an electret film is known. Thiselectrostatic induction power generating device disclosed in JapaneseNational Patent Publication Gazette No. 2005-529574 is constituted by amovable electrode, a fixed electrode and an electret film made of acharge holding material of a resin material such as Teflon (registeredtrademark) formed on the fixed electrode. In this electrostaticinduction power generating device, the movable electrode repeatedlyvibrates by receiving inertial force, so that electric charges inducedin the movable electrode with electric charges stored in the electretfilm are changed to output the changed amount of electric charges as acurrent.

In the aforementioned electrostatic induction power generating deviceemploying the electret film, however, the electrostatic induction powergenerating device receives a physical impact and the movable electrodeand the electret film come into physical contact with each other,whereby the amount of electric charges stored in the electret film isdisadvantageously changed.

DISCLOSURE OF THE INVENTION

The present invention has been proposed in order to solve theaforementioned problems, and an object of the present invention is toprovide an electrostatic operation device capable of inhibiting theamount of electric charges stored in an electret film from change due toa physical impact.

An electrostatic operation device according to a first aspect of thepresent invention comprises a first electrode, an electret film soformed as to be opposed to the first electrode at an intervaltherebetween and a member inhibiting the first electrode and theelectret film from moving close to each other within a prescribedinterval.

As hereinabove described, this electrostatic operation device accordingto the first aspect comprises the member inhibiting the first electrodeand the electret film from moving close to each other within theprescribed interval, whereby the first electrode and the electret filmcan be inhibited from coming into contact with each other due to aphysical impact, and hence the amount of electric charges stored in theelectret film can be inhibited from change due to contact between thefirst electrode and the electret film.

The aforementioned electrostatic operation device according to the firstaspect preferably further comprises a second electrode so provided as tobe opposed to the first electrode at an interval therebetween. Accordingto this structure, the first electrode and the second electrode areelectrically connected to each other, whereby electrostatic induction iscaused in the first electrode and the second electrode by electriccharges stored in the electret film. This potential difference betweenthe first electrode and the second electrode is extracted, whereby powercan be generated.

In this case, an end of a surface of the member on a side of one of thefirst electrode and the second electrode is preferably chamfered.According to this structure, the end of the surface of the member on theside of the first electrode has a smooth shape, and hence the firstelectrode can be inhibited from catching the member when the firstelectrode is moving by vibration.

The aforementioned electrostatic operation device comprising the firstelectrode and the second electrode preferably further comprises a firstsubstrate formed with the first electrode and a second substrate formedwith the second electrode, wherein the member is preferably formed on asurface of one of the first substrate and the second substrate.According to this structure, the first and second electrodes and theelectret film can be easily inhibited from coming into contact with eachother.

The aforementioned electrostatic operation device comprising the firstelectrode and the second electrode preferably further comprises a firstsubstrate formed with the first electrode, wherein the member may beprovided on a position between the first substrate and the secondelectrode at intervals from the first substrate and the secondelectrode.

The aforementioned electrostatic operation device comprising the firstelectrode and the second electrode preferably further comprises aprotective film formed to cover a surface not formed with the electretfilm in the surfaces of the first and second electrodes. According tothis structure, the protective film can inhibit the surface not formedwith the electret film in the surfaces of the first and secondelectrodes from coming into contact with the electret film.

In the aforementioned electrostatic operation device according to thefirst aspect, the member preferably has a function as a stopperinhibiting the first electrode and the electret film from coming intocontact with each other or a spacer keeping an interval between thefirst electrode and the electret film constant. According to thisstructure, the member is employed as the stopper, whereby the firstelectrode and the electret film can be easily inhibited from coming intocontact with each other. Further, the member is employed as the spacer,whereby the interval between the first electrode and the electret filmcan be kept constant.

The aforementioned electrostatic operation device according to the firstaspect preferably further comprises a guard electrode for inhibiting acomponent other than a component in a direction perpendicular to a mainsurface of the electret film in an electric field resulting fromelectric charges stored in the electret film from generation, providedto be adjacent to the electret film. According to this structure, theelectric field can be inhibited from reaching a position not opposed tothe main surface of the electret film and hence difference in potentialsbetween a potential at a position opposed to the main surface of theelectret film and a potential at the position not opposed to theelectret film can be increased. Thus, difference between the amount ofelectric charges stored in the first electrode by electrostaticinduction in a case where the first electrode is at the position opposedto the electret film and the amount of electric charges stored in thefirst electrode by electrostatic induction in a case where the firstelectrode is at the position not opposed to the electret film can beincreased. Consequently, the amount of power generation can beincreased.

In this case, the electrostatic operation device preferably furthercomprises a second electrode so provided as to be opposed to the firstelectrode at an interval therebetween, wherein the member is so formedas to be stacked on a surface of the guard electrode on a side of one ofthe first electrode and the second electrode. According to thisstructure, a planar region on the surface of the fixed substrate forarranging the member and the guard electrode is reduced as compared witha case where the member and the guard electrode are arranged ondifferent planar positions without being stacked with each other, andhence size in the electrostatic operation device can be reduced.

In the aforementioned electrostatic operation device according to thefirst aspect, the member inhibiting the first electrode and the electretfilm from coming into contact with each other preferably functions as aguard electrode for inhibiting a component other than a component in adirection perpendicular to a main surface of the electret film in anelectric field resulting from electric charges stored in the electretfilm from generation, provided to be adjacent to the electret film.According to this structure, the member inhibiting the first electrodeand the electret film from coming into contact with each other functionsalso as the guard electrode and hence the number of components can bereduced dissimilarly to a case where the member and the guard electrodeare separately formed.

The aforementioned electrostatic operation device according to the firstaspect preferably further comprises a first substrate formed with thefirst electrode, wherein the first electrode is embedded in the firstsubstrate. According to this structure, the surface of the firstsubstrate has no irregularities and hence the first electrode can beinhibited from coming into contact with and catching the member when thefirst electrode is moving by vibration.

In the aforementioned electrostatic operation device according to thefirst aspect, the member is preferably formed between the electret filmand the first electrode. According to this structure, the electret filmand the first electrode can be easily inhibited from coming into contactwith each other and the interval between the electret film and the firstelectrode can be kept at a prescribed interval or more.

The aforementioned electrostatic operation device according to the firstaspect further may comprise a first substrate formed with the firstelectrode, wherein the first substrate may be supported by the member tobe able to vibrate.

The aforementioned electrostatic operation device according to the firstaspect further may comprise a second substrate formed with the electretfilm, wherein the second substrate may be supported by the member to beable to vibrate.

The aforementioned electrostatic operation device according to the firstaspect preferably further comprises a groove shaped recess portion and aprojecting portion provided on a surface of one of said first electrodeand said second electrode, wherein the electret film is preferably soformed as to be embedded in at least a bottom surface of the recessportion. According to this structure, the projecting portion can inhibitthe other of the first and second electrodes and the electret film fromcoming into contact with each other, and hence the amount of electriccharges stored in the electret film can be inhibited from change.

In this case, the groove shaped recess portion is so formed that a widthis preferably increased from a bottom surface of the recess portiontoward an open upper end thereof. According to this structure, sidesurfaces of the recess portion are inclined and hence the other of thefirst electrode and the second electrode can be inhibited from catchingthe side surfaces of the recess portion.

In the aforementioned electrostatic operation device where the electretfilm is so formed as to be embedded in at least the bottom surface ofthe recess portion, a conductive layer is preferably formed on a surfaceof the projecting portion. According to this structure, the conductivelayer can inhibit a component other than a component in a directionperpendicular to a main surface of the electret film in an electricfield resulting from electric charges stored in the electret film fromgeneration, and hence the electric field can be inhibited from reachinga position not opposed to the main surface of the electret film. Thus,difference between a potential of a position opposed to the main surfaceof the electret film and a potential of the position not opposed to theelectret film can be increased, and hence difference between the amountof electric charges stored in the other of the first electrode and thesecond electrode by electrostatic induction in a case where the other ofthe first electrode and the second electrode is at the position opposedto the electret film and the amount of electric charges stored in theother of the first electrode and the second electrode by electrostaticinduction in a case where the other of the first electrode and thesecond electrode is at the position not opposed to the electret film canbe increased. Consequently, the amount of power generation can beincreased.

In the aforementioned electrostatic operation device where the electretfilm is so formed as to be embedded in at least the bottom surface ofthe recess portion, an insulating film having a smaller breakdownvoltage than the electret film is preferably formed on a surface of theprojecting portion. According to this structure, even when the electretfilm and the insulating film are simultaneously made electret, theinsulating film first causes dielectric breakdown due to the smallerbreakdown voltage of the insulating film than the electret film, andhence the electret film can store a larger number of electric chargesand the amounts of electric charges stored in the electret film and theinsulating film are made different from each other. Thus, an intensityof an electric field on a surface of the electret film and an intensityof an electric field on a surface of the insulating film can be madedifferent from each other.

In the aforementioned electrostatic operation device where the electretfilm is so formed as to be embedded in at least the bottom surface ofthe recess portion, the electret film is preferably formed on the bottomsurface of the recess portion to have a thickness smaller than a depthof the recess portion. According to this structure, the electret filmdoes not protrude from an opening of the recess portion and hence theelectret film and the other of the first electrode and the secondelectrode can be inhibited from coming into contact with each other.

In the aforementioned electrostatic operation device where the electretfilm is so formed as to be embedded in at least the bottom surface ofthe recess portion, an end of a surface of the projecting portion on aside of one of the first electrode and the second electrode ispreferably formed in a rounded shape or a chamfered shape. According tothis structure, the projecting portion and the other of the firstelectrode and the second electrode can be easily inhibited from cominginto contact with each other.

In the aforementioned electrostatic operation device where the electretfilm is so formed as to be embedded in at least the bottom surface ofthe recess portion, a charge outflow inhibition film is preferablyformed on a surface of the electret film. According to this structure,electric charges can be easily inhibited from flowing out of theelectret film.

In the aforementioned electrostatic operation device where the electretfilm is so formed as to be embedded in at least the bottom surface ofthe recess portion, the electret film formed to be embedded in thegroove shaped recess portion is preferably oblongly formed in plan view.According to this structure, an intensity of an electric field on asurface of the electret film and an intensity of an electric field on asurface of a region not formed with the electret film can be easily madedifferent from each other.

In the aforementioned electrostatic operation device according to thefirst aspect, the member is preferably formed on a surface of theelectret film. According to this structure, a width of the electrostaticoperation device can be reduced by a width of the member dissimilarly toa case where the member is formed around the electret film.

In this case, at least a part of the member is preferably formed by amember softer than the electret film. According to this structure, themember is deformed to absorb an impact even when an impact is applied tothe member, and hence deformation of the electret film can besuppressed. Further, the member is formed by an elastic member, wherebythe member can be inhibited from breakage even when an impact is appliedto the member, and hence reduction in a surface potential resulting fromdeposition of fragments of the member caused by breakage on the surfaceof the electret film can be suppressed. The fragments of the member aredeposited on the surface of the electret film, whereby an electric fieldon the surface of the electret film can be inhibited from hindering.

The aforementioned electrostatic operation device where the member isformed on the surface of the electret film preferably further comprisesa conductive layer formed on a surface of the member. According to thisstructure, injection of electric charges into the member can besuppressed by the conductive layer when electric charges are injectedinto the electret film by corona discharge.

In the aforementioned electrostatic operation device where the member isformed on the surface of the electret film, the member is preferably soformed that a width is reduced toward a side on which the electret filmis not formed. According to this structure, friction between the otherof the first and second electrodes and the member can be reduced whenthe other of the first electrode and the second electrode comes intocontact with the member dissimilarly to a case where the width of themember does not vary.

An electrostatic operation device according to a second aspect of thepresent invention comprises a first electrode, a second electrodeprovided to be adjacent to the first electrode at an intervaltherebetween, an electret film formed to be opposed to the firstelectrode and the second electrode and a member having a function as astopper inhibiting the first and second electrodes and the electret filmfrom coming into contact with each other or a spacer keeping an intervalbetween the first and second electrodes and the electret film constant,between the first and second electrodes and the electret film.

As hereinabove described, this electrostatic operation device accordingto the second aspect comprises the member as the stopper inhibiting thefirst and second electrodes and the electret film from coming intocontact with each other, whereby the first and second electrodes and theelectret film can be inhibited from coming into contact with each otherdue to a physical impact, and hence the amount of electric chargesstored in the electret film can be inhibited from change due to contactbetween the first and second electrodes and the electret film. Further,the electrostatic operation device comprises the member as the spacerkeeping the interval between the first and second electrodes and theelectret film constant, whereby the interval between the first andsecond electrodes and the electret film can be kept constant and hencethe amount of power generation can be stabilized.

An electrostatic operation device according to a third aspect of thepresent invention comprises a first electrode, a second electrodeprovided to be adjacent to the first electrode at an intervaltherebetween, a substrate to be opposed to the first electrode and thesecond electrode and provided with a projecting portion and a recessportion, and an electret film formed to be embedded in a bottom surfaceof the recess portion provided on the substrate, wherein the projectingportion provided on the substrate has a function as a stopper inhibitingthe first and second electrodes and the electret film from coming intocontact with each other or a spacer keeping an interval between thefirst and second electrodes and the electret film constant.

In this electrostatic operation device according to the third aspect, ashereinabove described, the projecting portion of the substrate has thefunction as the stopper to inhibit the first and second electrodes andthe electret film from coming into contact with each other, whereby thefirst and second electrodes and the electret film can be inhibited fromcoming into contact with each other due to a physical impact, and hencethe amount of electric charges stored in the electret film can beinhibited from change due to contact between the first and secondelectrodes and the electret film. The projecting portion of thesubstrate has the function as the spacer keeping the interval betweenthe first and second electrodes and the electret film constant, wherebythe interval between the first and second electrodes and the electretfilm can be kept constant and hence the amount of power generation canbe stabilized.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] A sectional view of an electrostatic induction power generatingdevice according to a first embodiment of the present invention.

[FIG. 2] A sectional view taken along the line 100-100 in FIG. 1.

[FIG. 3] A sectional view taken along the line 110-110 in FIG. 1.

[FIG. 4] A sectional view of an electrostatic induction power generatingdevice according to a second embodiment of the present invention.

[FIG. 5] A sectional view of an electrostatic induction power generatingdevice according to a third embodiment of the present invention.

[FIG. 6] A sectional view taken along the line 120-120 in FIG. 5.

[FIG. 7] A sectional view taken along the line 130-130 in FIG. 5.

[FIG. 8] A sectional view of an electrostatic induction power generatingdevice according to a fourth embodiment of the present invention.

[FIG. 9] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to a fifthembodiment of the present invention.

[FIG. 10] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to a sixthembodiment of the present invention.

[FIG. 11] A sectional view of an electrostatic induction powergenerating device according to a seventh embodiment of the presentinvention.

[FIG. 12] A sectional view taken along the line 140-140 in FIG. 11.

[FIG. 13] A sectional view taken along the line 150-150 in FIG. 11.

[FIG. 14] A sectional view for illustrating a power generating operationof the electrostatic induction power generating device according to theseventh embodiment of the present invention.

[FIG. 15] A sectional view of an electrostatic induction powergenerating device according to an eighth embodiment of the presentinvention.

[FIG. 16] A diagram showing a condition of an electromagnetical fieldsimulation for confirming effects of guard electrodes according to theeighth embodiment.

[FIG. 17] A diagram showing lines of electric force by electric chargesstored in the electret film.

[FIG. 18] A sectional view of an electrostatic induction powergenerating device according to a ninth embodiment of the presentinvention.

[FIG. 19] A sectional view of an electrostatic induction powergenerating device according to a tenth embodiment of the presentinvention.

[FIG. 20] A sectional view of an electrostatic induction powergenerating device according to an eleventh embodiment of the presentinvention.

[FIG. 21] A sectional view of an electrostatic induction powergenerating device according to a twelfth embodiment of the presentinvention.

[FIG. 22] A sectional view of an electrostatic induction powergenerating device according to a thirteenth embodiment of the presentinvention.

[FIG. 23] A sectional view taken along the line 160-160 in FIG. 22.

[FIG. 13] A sectional view taken along the line 170-170 in FIG. 22.

[FIG. 25] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to afourteenth embodiment of the present invention.

[FIG. 26] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to a fifteenthembodiment of the present invention.

[FIG. 27] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to a sixteenthembodiment of the present invention.

[FIG. 28] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to aseventeenth embodiment of the present invention.

[FIG. 29] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to aneighteenth embodiment of the present invention.

[FIG. 30] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to anineteenth embodiment of the present invention.

[FIG. 31] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to a twentiethembodiment of the present invention.

[FIG. 32] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to atwenty-first embodiment of the present invention.

[FIG. 33] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to atwenty-second embodiment of the present invention.

[FIG. 34] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to atwenty-third embodiment of the present invention.

[FIG. 35] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to atwenty-fourth embodiment of the present invention.

[FIG. 36] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to atwenty-fifth embodiment of the present invention.

[FIG. 37] A sectional view of an electrostatic induction powergenerating device according to a twenty-sixth embodiment of the presentinvention.

[FIG. 38] A sectional view of an electrostatic induction powergenerating device according to a twenty-seventh embodiment of thepresent invention.

[FIG. 39] A sectional view of an electrostatic induction powergenerating device according to a twenty-eighth embodiment of the presentinvention.

[FIG. 40] A sectional view taken along the line 180-180 in FIG. 39.

[FIG. 41] A sectional view of an electrostatic induction powergenerating device according to a twenty-ninth embodiment of the presentinvention.

[FIG. 42] A sectional view of an electrostatic induction powergenerating device according to a thirtieth embodiment of the presentinvention.

[FIG. 43] A sectional view of an electrostatic induction powergenerating device according to a thirty-first embodiment of the presentinvention.

[FIG. 44] A sectional view of an electrostatic induction powergenerating device according to a thirty-first embodiment of the presentinvention.

[FIG. 45] A sectional view taken along the line 190-190 in FIG. 43.

[FIG. 46] A sectional view of an electrostatic induction powergenerating device according to a thirty-second embodiment of the presentinvention.

[FIG. 47] A sectional view taken along the line 200-200 in FIG. 46.

[FIG. 48] A sectional view of an electrostatic induction powergenerating device according to a thirty-third embodiment of the presentinvention.

[FIG. 49] A sectional view taken along the line 210-210 in FIG. 48.

[FIG. 50] A sectional view of an electrostatic induction powergenerating device according to a thirty-fourth embodiment of the presentinvention.

[FIG. 51] A sectional view of an electrostatic induction powergenerating device according to a thirty-fifth embodiment of the presentinvention.

[FIG. 52] A sectional view of an electrostatic induction powergenerating device according to a thirty-sixth embodiment of the presentinvention.

[FIG. 53] A sectional view of a movable electrode portion according to athirty-seventh embodiment of the present invention.

[FIG. 54] A sectional view of an electrostatic induction powergenerating device according to a thirty-eighth embodiment of the presentinvention.

[FIG. 55] A sectional view of an electrostatic induction powergenerating device according to a thirty-ninth embodiment of the presentinvention.

[FIG. 56] A sectional view of an electrostatic induction powergenerating device according to a fortieth embodiment of the presentinvention.

[FIG. 57] A sectional view of an electrostatic induction powergenerating device according to a forty-first embodiment of the presentinvention.

[FIG. 58] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to amodification of the fifteenth embodiment of the present invention.

[FIG. 59] A sectional view of an electrostatic induction powergenerating device according to a first modification of the firstembodiment of the present invention.

[FIG. 60] A sectional view of an electrostatic induction powergenerating device according to a second modification of the firstembodiment of the present invention.

[FIG. 61] A sectional view of an electrostatic induction powergenerating device according to a third modification of the firstembodiment of the present invention.

[FIG. 62] A sectional view of an electrostatic induction powergenerating device according to a fourth modification of the firstembodiment of the present invention.

[FIG. 63] A sectional view of an electrostatic induction powergenerating device according to a modification of the thirty-eighthembodiment of the present invention.

[FIG. 64] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to amodification of the seventeenth embodiment of the present invention.

[FIG. 65] A sectional view of a fixed electrode portion of anelectrostatic induction power generating device according to amodification of each of the seventh to twelfth embodiments of thepresent invention.

BEST MODES FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be hereinafter described withreference to the drawings.

First Embodiment

A structure of an electrostatic induction power generating device 1according to a first embodiment will be described with reference toFIGS. 1 to 3. The first embodiment of the present invention is appliedto the electrostatic induction power generating device 1 employed as anexemplary electrostatic operation device.

The electrostatic induction power generating device 1 according to thefirst embodiment is constituted by a fixed electrode portion 2 and amovable electrode portion 3, as shown in FIG. 1. The first embodimentwill be now described in detail.

As shown in FIG. 1, in the fixed electrode portion 2, a groove shapedrecess portion 401 a and a projecting portion 401 b for inhibiting anelectret film 5 and a movable electrode 8, described later, from cominginto contact with each other are formed on a surface of a fixedelectrode 4 made of silicon. The fixed electrode 4 is an example of the“second electrode” in the present invention. The projecting portion 401b is an example of the “member” in the present invention. According tothe first embodiment, the projecting portion 401 b has a function as astopper inhibiting the movable electrode 8 and the electret film 5 fromcoming into contact with each other. As shown in FIG. 2, the grooveshaped recess portion 401 a is rectangularly formed. The rectangularelectret film 5 made of an organic material such as PTFE or a siliconoxide film, having a thickness of about 0.1 μm to about 50 μm is soformed as to fill up a bottom surface of the groove shaped recessportion 401 a. The interdigital conductive layer 6 is formed on an uppersurface of the electret film 5.

As shown in FIG. 1, in the movable electrode portion 3, the movableelectrode 8 is so formed on a surface of a movable substrate 7 made ofquartz as to be opposed to the electret film 5. The movable electrode 8is an example of the “first electrode” in the present invention. Asshown in FIG. 3, the movable electrode 8 is interdigitally formed.

A power generating operation of the electrostatic induction powergenerating device 1 according to the first embodiment of the presentinvention will be now described with reference to FIG. 1.

When no vibration is applied to the electrostatic induction powergenerating device 1, the electret film 5 and the movable electrode 8 arearranged to be opposed to each other at a prescribed interval, as shownin FIG. 1. At this time, positive electric charges or negative electriccharges are stored in the surface of the electret film 5. Chargesopposite to the electric charges stored in the electret film 5 on a sideof the movable electrode 8 are induced in the movable electrode 8 byelectrostatic induction.

Then, the movable electrode 8 moves to a position opposed to theconductive layer 6 from a position opposed to the electret film 5 shownin FIG. 1 by applying horizontal vibration (in a direction X) to theelectrostatic induction power generating device 1 and moving the movableelectrode 8 in the direction X. Thus, electrostatic force running to themovable electrode 8 is reduced, and hence the amount of electric chargesinduced in the movable electrode 8 is reduced. Thereafter theelectrostatic induction power generating device 1 vibrates in thehorizontal direction (direction X), so that the amount of the electriccharges induced in the movable electrode 8 is increased when theelectret film 5 and the movable electrode 8 are at the opposed positionshown in FIG. 1. This changed amount of the electric charges induced inthe movable electrode 8 is extracted as a current, so that theelectrostatic induction power generating device 1 can generate power.

According to the first embodiment, as hereinabove described, theelectrostatic induction power generating device 1 comprises theprojecting portion 401 b for inhibiting the movable electrode 8 and theelectret film 5 from coming into contact with each other, whereby themovable electrode 8 can be inhibited from moving in a direction Z(vertical direction) shown in FIG. 1 by a physical impact and cominginto contact with the electret film 5, and hence the amount of electriccharges stored in the electret film 5 can be inhibited from change dueto contact between the movable electrode 8 and the electret film 5.Further, the fixed electrode 4 and the projecting portion 401 b areintegrally formed, whereby adhesion between the fixed electrode 4 andthe projecting portion 401 b is excellent and hence the fixed electrode4 and the projecting portion 401 b can be inhibited from separation evenwhen force by the contact between the movable electrode 8 and theelectret film 5 in vibration is applied to the projecting portion 401 b.Additionally, the fixed electrode 4 and the projecting portion 401 b areintegrally formed, whereby the number of components can be reduceddissimilarly to a case where the fixed electrode 4 and the projectingportion 401 b are formed by different members.

Second Embodiment

Referring to FIG. 4, an electrostatic induction power generating device1 a where a movable substrate 7 is in contact with a projecting portion401 b will be described in this second embodiment dissimilarly to theaforementioned first embodiment.

In an electrostatic induction power generating device la according tothis second embodiment, the projecting portion 401 b provided on a fixedelectrode 4 is formed in contact with the movable substrate 7 as shownin FIG. 4.

According to the second embodiment, the projecting portion 401 b has afunction as a stopper inhibiting the movable electrode 8 and theelectret film 5 from coming into contact with each other and also has afunction as a spacer keeping an interval between the movable electrode 8and the electret film 5 constant. The remaining structure of the secondembodiment is similar to that of the aforementioned first embodiment.

The effects of the second embodiment are similar to those of theaforementioned first embodiment.

Third Embodiment

Referring to FIGS. 5 to 7, an electrostatic induction power generatingdevice b where stopper films 9 are formed on a surface of an electretfilm 5 a will be described in this third embodiment dissimilar to theaforementioned first embodiment.

In a fixed electrode portion 2 a according to this third embodiment, theelectret film 5 a is formed on a surface of a fixed electrode 4 a asshown in FIG. 5. The fixed electrode 4 a is an example of the “secondelectrode” in the present invention. As shown in FIGS. 5 and 6, oblongconductive layer 6 a is formed on a surface of the electret film 5 a.According to the third embodiment, the stopper films 9 formed by aninsulating film such as a plasma silicon oxide film or a plasma siliconnitride film softer than the electret film 5 a, a tape constituted by asubstrate and an adhesive material, a conductive material andcombination of these are formed to be adjacent to the conductive layer 6a. The stopper films 9 are examples of the “member” in the presentinvention. A height of each of the stopper films 9 is formed to belarger than that of the conductive layer 6 a. A charge outflowinhibition film made of MSQ may be formed on a surface of the electretfilm 5 a.

As shown in FIGS. 5 and 7, a movable electrode 8 a is formed on asurface of a movable substrate 7. As shown in FIG. 7, the movableelectrode 8 a is oblongly formed.

As shown in FIG. 5, in an electrostatic induction power generatingdevice 1 b according to the third embodiment, the fixed electrode 4 aand the movable electrode 8 a relatively move in a direction Y, therebygenerating power.

According to the third embodiment, as hereinabove described, the stopperfilms 9 are formed on the surface of the electret film 5 a, whereby awidth of the electrostatic induction power generating device 1 b can bereduced by a width of the stopper films 9 dissimilarly to a case offorming the stopper films 9 around the electret film 5 a. The stopperfilms 9 are formed by the insulating film such as a plasma oxide film ora plasma nitride film softer (having a Young's modulus lower) than theelectret film 5 a or the tape constituted by a substrate and an adhesivematerial, whereby the stopper films 9 are deformed to absorb an impacteven when the impact is applied to the stopper films 9, and hencedeformation of the electret film 5 a can be suppressed. Further, thestopper films 9 are formed by an elastic member, whereby the stopperfilms 9 can be inhibited from breakage even when an impact is applied tothe stopper films 9, and hence reduction in a surface potentialresulting from deposition of fragments of the stopper films 9 caused bybreakage on the surface of the electret film 5 a can be suppressed. Thefragments of the stopper films 9 are deposited on the surface of theelectret film 5 a, whereby an electric field on the surface of theelectret film 5 a can be inhibited from hindering.

Fourth Embodiment

Referring to FIG. 8, an electrostatic induction power generating device1 c where a movable substrate 7 is in contact with stopper films 9 willbe described in this fourth embodiment dissimilarly to theaforementioned third embodiment.

In an electrostatic induction power generating device 1 c according tothis fourth embodiment, the stopper films 9 provided on a surface of anelectret film 5 a are formed in contact with the movable substrate 7 asshown in FIG. 8. The remaining structure of the fourth embodiment issimilar to that of the aforementioned third embodiment.

The effects of the fourth embodiment are similar to those of theaforementioned third embodiment.

Fifth Embodiment

Referring to FIG. 9, a fixed electrode portion 2 b where conductivelayers 10 are formed on surfaces of stopper films 9 will be described inthis fifth embodiment dissimilarly to the aforementioned thirdembodiment.

In the fixed electrode portion 2 b according to this fifth embodiment,conductive layers 10 are formed on the surfaces of the stopper films 9as shown in FIG. 9. The remaining structure of the fifth embodiment issimilar to that of the aforementioned third embodiment.

According to the fifth embodiment, as hereinabove described, theconductive layers 10 are formed on the surfaces of the stopper films 9,whereby injection of electric charges into the stopper films 9 can besuppressed by the conductive layers 10 when electric charges areinjected into the electret film 5 a by corona discharge. Thus,electrostatic force exerted on the movable electrode 8 a can besuppressed by the stopper films 9.

Sixth Embodiment

Referring to FIG. 10, a fixed electrode portion 2 c where stopper films9 a are so formed that widths thereof are reduced toward a side of amovable electrode 8 a will be described in this sixth embodimentdissimilarly to the aforementioned third embodiment.

In the fixed electrode portion 2 c according to this sixth embodiment,the stopper films 9 a are so formed that the widths thereof are reducedtoward the side of the movable electrode 8 a (see FIG. 5) as shown inFIG. 10. The stopper films 9 a are examples of the “member” in thepresent invention. The remaining structure of the sixth embodiment issimilar to that of the aforementioned third embodiment.

According to the sixth embodiment, as hereinabove described, the stopperfilms 9 a are so formed that the widths thereof are reduced toward theside of the movable electrode 8 a, whereby friction between the movableelectrode 8 a and the stopper films 9 a can be reduced when the movableelectrode 8 a and the stopper films 9 a (see FIG. 5) come into contactwith each other dissimilarly to a case where the widths of the stopperfilms 9 do not vary.

Seventh Embodiment

Referring to FIGS. 11 to 13, a structure of an electrostatic inductionpower generating device 1 d according to a seventh embodiment will bedescribed.

The electrostatic induction power generating device 1 d according tothis seventh embodiment is constituted by a fixed substrate 11 made ofglass, a movable substrate 21 made of glass and a column portion 31 madeof silicon as shown in FIG. 11. The movable substrate 21 is mounted on aframe portion 23 through spring portions 22 as shown in FIG. 13. Thecolumn portion 31 is formed on an upper surface of the fixed substrate11 and the frame portion 23 is fixed on an upper surface of the columnportion 31. A detailed description will be made hereinafter.

As shown in FIGS. 11 and 12, an interdigital fixed electrode 12 made ofAu or Al having a thickness of about 1 μm and a width W1 of about 100 μmis formed on the upper surface of the fixed substrate 11 made of glasshaving a thickness of about 0.5 mm. The fixed electrode 12 is an exampleof the “second electrode” in the present invention. An interdigitalelectret film 13 made of Teflon (registered trademark) having athickness of about 1 μm and the width W1 of about 100 μm is so formed asto be stacked on the upper surface of the fixed electrode 11. Chargesare injected by corona discharge so that the electret film 13 iscontrolled to a potential of about 1000 V.

According to the seventh embodiment, an interdigital stopper film 14made of a silicon oxide film or a silicon nitride film having athickness of about 20 μm and a width W2 of about 100 μm is formed on theupper surface of the fixed substrate 11 to be adjacent to the fixedelectrode 12 at intervals D of about 10 μm from the fixed electrode 12.The stopper film 14 is an example of the “member” in the presentinvention. In other words, the stopper film 14 is so formed as to have athickness not causing contact between a movable electrode 24, describedlater, and the electret film 13 when the movable electrode 24 comesclose to the electret film 13 by vibration.

The electret film 13 and the fixed electrode 12 are opposed to thestopper film 14 at an interval so that teeth forming the interdigitalelectret film 13 and the interdigital fixed electrode 12 do not overlapwith teeth forming the interdigital stopper film 14. The column portion31 is formed along peripheral portions of the fixed substrate 11 and theframe portion 23.

As shown in FIG. 11, the movable electrode 24 made of Au or Al having athickness of about 0.5 μm and a width of about 100 μm is formed on alower surface of the movable substrate 21 made of glass having athickness of about 0.5 mm. The movable electrode 24 is an example of the“first electrode” in the present invention. The fixed substrate 11 andthe movable substrate 21 are set to be opposed at an interval of about30 μm by the column portion 31.

As shown in FIG. 13, the movable electrode 24 is interdigitally formedsimilarly to the electret film 13 and the fixed electrode 12 shown inFIG. 12. As shown in FIG. 11, the electret film 13 and the movableelectrode 24 are arranged to be opposed to each other when no vibrationis applied to the electrostatic induction power generating device 1 d.

A power generating operation of the electrostatic induction powergenerating device 1 d according to the seventh embodiment of the presentinvention will be now described with reference to FIGS. 11 and 14.

When no vibration is applied to the electrostatic induction powergenerating device 1 d, the electret film 13 and the movable electrode 24are arranged to be opposed to each other at a prescribed interval, asshown in FIG. 11. At this time, positive electric charges or negativeelectric charges are stored in the surface of the electret film 13.Charges opposite to the electric charges stored in the electret film 13on a side of the movable electrode 24 are induced in the movableelectrode 24 by electrostatic induction.

Then, the movable electrode 24 moves to a position opposed to thestopper film 14 shown in FIG. 14 from a position opposed to the electretfilm 13 shown in FIG. 11 by applying horizontal vibration (in adirection X) to the electrostatic induction power generating device 1 dand moving the movable electrode 24 in the direction X. The influence ofan electric field resulting from electric charges stored in the electretfilm 13 on the movable electrode 24 is smaller at the position opposedto the stopper film 14 shown in FIG. 14 than at the position opposed tothe electret film 13 shown in FIG. 11, and hence the amount of electriccharges stored in the movable electrode 24 is reduced. Thereafter themovable electrode 24 is returned to a state shown in FIG. 11 by thespring portions 22, to be opposed to the electret film 13, therebyincreasing the amount of electric charges stored in the movableelectrode 24. Further, the movable electrode 24 moves in a directionopposite to the direction X shown in FIG. 14 by inertial force, to beopposed to the stopper film 14, thereby reducing the amount of electriccharges stored in the movable electrode 24. Thus, the changed amount ofelectric charges stored in the movable electrode 24, induced byrepeating lateral (horizontal) vibration is extracted as a alternatingcurrent by a wire (not shown) connected to the fixed electrode 12 andthe movable electrode 24, thereby generating power. While FIG. 14 showsthat the operating range of the movable electrode 24 is movement to thestopper film 14 adjacent to the opposed electret film 13, the movableelectrode 24 may be formed to move to the stopper film 14 next to theadjacent stopper film 14.

According to the seventh embodiment, as hereinabove described, theelectrostatic induction power generating device 1 d comprises thestopper film 14 inhibiting the movable electrode 24 and the electretfilm 13 from coming into contact with each other, whereby the movableelectrode 24 can be inhibited from moving in a direction Z (verticaldirection) shown in FIG. 14 by a physical impact and coming into contactwith the electret film 13, and hence the amount of electric chargesstored in the electret film 13 can be inhibited from change due tocontact between the movable electrode 24 and the electret film 13.

Eighth Embodiment

Referring to FIG. 15, an electrostatic induction power generating device1 e where a guard electrode 15 is formed on an upper surface of a fixedsubstrate 11 will be described in this eighth embodiment dissimilarly tothe aforementioned seventh embodiment.

In this electrostatic induction power generating device 1 e according tothe eighth embodiment, the guard electrode 15 made of Cu, Au or Alhaving a thickness of about 20 μm and a width of about 100 μm is formedon the upper surface of the fixed substrate 11 to be adjacent to thefixed electrode 12 and an electret film 13 formed on the fixed electrode12, as shown in FIG. 15. This guard electrode 15 has a functioninhibiting components other than a component in a directionperpendicular to a main surface of the electret film 13 in an electricfield resulting from electric charges stored in the electret film 13from generation. More specifically, existence of the guard electrode 15inhibits the electric field resulting from the electric charges storedin the electret film 13 from reaching around on the stopper film 14, andhence change in the capacitance of electric charges stored in themovable electrode 24 in changing a position of the movable electrode 24can be increased. This point has already been confirmed by a simulation,described later, conducted by inventors of this application. A potentialof the guard electrode 15 is controlled to 0 V. A stopper film 14 ahaving a thickness of about 1 μm is formed to be stacked on an uppersurface of the guard electrode 15. The stopper film 14 a is an exampleof the “member” in the present invention. A height of an upper surfaceof the stopper film 14 a is formed to be at least a height enough tosuppress contact between the electret film 13 and the movable electrode24 by vibration. The remaining structure of the eighth embodiment issimilar to that of the seventh embodiment.

According to the eighth embodiment, as hereinabove described, the guardelectrode 15 for inhibiting the components other than the component inthe direction perpendicular to the main surface of the electret film 13in the electric field resulting from the electric charges stored in theelectret member 13 from generation is provided to be adjacent to theelectret film 13, whereby the electric field can be inhibited fromreaching a position not opposed to the main surface of the electret film13 and hence difference in potentials between a position opposed to themain surface of the electret film 13 and the position not opposed to theelectret film 13 can be increased. Thus, difference between the amountof electric charges stored in the movable electrode 24 by electrostaticinduction in a case where the movable electrode 24 is at the positionopposed to the electret film 13 and the amount of electric chargesstored in the movable electrode 24 by electrostatic induction in a casewhere the movable electrode 24 is at the position not opposed to theelectret film 13 can be increased. Consequently, the amount of powergeneration can be increased.

According to the eighth embodiment, as hereinabove described, thestopper film 14 a is so formed as to be stacked on the surface of theguard electrode 15 on the side of the movable electrode 24, whereby aplanar region on the upper surface of the fixed substrate 11 forarranging the stopper film 14 a and the guard electrode 15 is reduced ascompared with a case where the stopper film 14 a and the guard electrode15 are arranged on different planar positions without being stacked witheach other, and hence size in the electrostatic induction powergenerating device 1 e can be reduced.

The remaining effects of the eighth embodiment are similar to those ofthe aforementioned seventh embodiment.

The simulation conducted for confirming the effects of the guardelectrode according to the aforementioned eighth embodiment will be nowdescribed with reference to FIGS. 16 and 17. In this simulation, it wasassumed that an electret film having a thickness of 1 μm and a width of100 μm and controlled to a potential of 1000 V was formed on aninsulating film (assuming glass) having a dielectric constant ε of 4, asshown in FIG. 16. Further, it was assumed that a guard electrode havinga width of about 100 μm was formed to be adjacent to the electret filmat an interval of 10 μm. It was assumed that four types of 1 μm, 10 μm,20 μm and 40 μm were employed as a thickness of the guard electrode. Apotential of the guard electrode is controlled to 0 V. It was assumedthat air having a dielectric constant ε of 1 filled up spaces betweenthe insulating film, the electret film and the guard electrode. Thendistribution of potentials on respective points by electric chargesstored in the electret film was obtained by an electromagnetical fieldsimulation. More specifically, differences in potentials between pointsA above the guard electrodes at the intervals from the guard electrodesand points B above the electret films at intervals from the electretfilms in cases where the thicknesses of the guard electrodes are 1 μm,10 μm, 20 μm and 40 μm are obtained respectively. Table 1 shows theresults of this experiment.

TABLE 1 Thickness of Difference in Potentials Guard Electrode betweenPoint A and Point B (μm) (V) 1 310 10 330 20 347 40 372

It is understood from the aforementioned Table 1 that the difference inthe potentials between the point A and the point B is increased as thethickness of the guard electrode is increased. This shows that thecomponents other than the component in the direction perpendicular tothe main surface of the electret film in the electric field resultingfrom the electric charges stored in the electret film is inhibited fromgeneration as the thickness of the guard electrode is increased, and theelectric field is inhibited from reaching the point A. Consequently, thedifference in the potentials between the point A and the point B isincreased. This is conceivably for the following reason: In other words,the lines of electric force are expanded also in directions other thanthe direction perpendicular to the main surface of the electret film ina state where no guard electrode is formed as shown in an upper figurein FIG. 17. In the case where the guard electrode is formed as to beadjacent to the electret film, however, it is conceivable thatdirections of the lines of electric force are uniformed in a directionopposed to the movable electrode by the guard electrode as shown in alower figure in FIG. 17 and hence the lines of electric force areinhibited from reaching the point A in FIG. 16. Consequently, thedifference in the potentials between the point A and the point B shownin FIG. 16 is conceivably increased when the guard electrode is formed.

Ninth Embodiment

Referring to FIG. 18, an electrostatic induction power generating device1 f where a fixed electrode 12 and a guard electrode 15a have the samethickness and are made of the same material will be described in thisninth embodiment dissimilarly to the aforementioned eighth embodiment.

In this electrostatic induction power generating device 1 f according tothe ninth embodiment, the guard electrode 15 a having the same thicknessof about 1 μm as the fixed electrode 12 is formed on an upper surface ofa fixed substrate 11 to be adjacent to the fixed electrode 12 having athickness of about 1 μm and an electret film 13 formed on the fixedelectrode 12 as shown in FIG. 18. The fixed electrode 12 and the guardelectrode 15 a are made of the same material (Al or Au, for example).Thus, the fixed electrode 12 and the guard electrode 15 a can besimultaneously formed and hence steps of forming the electrostaticinduction power generating device 1 b can be reduced. A stopper film 14b having a thickness of about 20 μm is formed on an upper surface of theguard electrode 15 a. The stopper film 14 b is an example of the“member” in the present invention. A height of an upper surface of thestopper film 14 b is formed to be a height enough to suppress contactbetween the electret film 13 and the movable electrode 24 by vibration.A potential of the guard electrode is controlled to 0 V. The remainingstructure is similar to that of the seventh embodiment.

The effects of the ninth embodiment are similar to those of theaforementioned seventh and eighth embodiments.

Tenth Embodiment

Referring to FIG. 19, an electrostatic induction power generating device1 g where ends of a surface of a stopper film 14 c on a side of amovable electrode 24 are chamfered will be described in this tenthembodiment dissimilarly to the aforementioned eighth embodiment.

In this electrostatic induction power generating device 1 g according tothe tenth embodiment, a guard electrode 15 having a thickness of about20 μm is formed on an upper surface of a fixed substrate 11 as shown inFIG. 10. The stopper film 14 c having a thickness of about 1 μm isformed on an upper surface of the guard electrode 15. The stopper film14 c is an example of the “member” in the present invention. At thistime, the ends of the surface of the stopper film 14 c on the side ofthe movable electrode 24 are chamfered according to the tenthembodiment. A height of an upper surface of the stopper film 14 c isformed to be a height enough to suppress contact between an electretfilm 13 and the movable electrode 24 by vibration. The remainingstructure is similar to that of the seventh embodiment.

According to the tenth embodiment, as hereinabove described, the ends ofthe surface of the stopper film 14 c on the side of the movableelectrode 24 are chamfered, whereby the ends of the surface of thestopper film 14 c on the side of the movable electrode 24 have smoothshapes and hence the stopper film 14 c and the movable electrode 24 canbe inhibited from coming into contact with and catching each other whenthe movable electrode 24 is moving by vibration.

The effects of the tenth embodiment are similar to those of theaforementioned seventh and eighth embodiments.

Eleventh Embodiment

Referring to FIG. 20, an electrostatic induction power generating device1 h where a movable electrode 24 a is so formed as to be embedded in amovable substrate 21 a will be described in this eleventh embodimentdissimilarly to the aforementioned tenth embodiment.

In this electrostatic induction power generating device 1 h according tothe eleventh embodiment, the movable electrode 24 a is so formed as tobe embedded in the movable substrate 21 a as shown in FIG. 20. Themovable substrate 21 a is an example of the “first substrate” in thepresent invention. The movable electrode 24 a is an example of the“first electrode” in the present invention. Thicknesses of the stopperfilm 14 c and the guard electrode 15 are so formed that the totalthickness of the stacked stopper film 14 c and guard electrode 15 islarger than the total thickness of the stacked fixed electrode 12 andelectret film 13. The remaining structure is similar to that of thetenth embodiment.

According to the eleventh embodiment, as hereinabove described, themovable electrode 24 a is so formed as to be embedded in the movablesubstrate 21 a, whereby the surface of the movable substrate 21 a has noirregularities and hence the movable electrode 24 a can be inhibitedfrom coming into contact with and catching the stopper film 14 c whenthe movable electrode 24 a is moving by vibration.

The effects of the eleventh embodiment are similar to those of theaforementioned seventh and eighth embodiments.

Twelfth Embodiment

Referring to FIG. 21, an electrostatic induction power generating device1 i where a movable substrate 21 b vibrates in a direction Z will bedescribed in this twelfth embodiment dissimilarly to the aforementionedseventh to eleventh embodiments.

In this electrostatic induction power generating device 1 i according tothe twelfth embodiment, a spring portion 22 a is formed on an uppersurface of the movable substrate 21 b as shown in FIG. 21, and themovable substrate 21 b moves in the direction Z to generate power. Whilean opposed area of the movable electrodes 24 and 24 a and the electretfilm 13 is changed to generate power in the aforementioned seventh toeleventh embodiments, a distance between the movable electrode 24 andthe electret film 13 is changed to generate power in the twelfthembodiment. The remaining structure is similar to that of the seventhembodiment.

The effects of the twelfth embodiment are similar to those of theaforementioned seventh embodiment.

Thirteenth Embodiment

Referring to FIGS. 22 to 24, an electrostatic induction power generatingdevice 1 j where an electret film 43 is so formed as to be embedded inbottom surfaces of recess portions 421 will be described in thisthirteenth embodiment dissimilarly to the aforementioned first totwelfth embodiments.

This electrostatic induction power generating device 1 j according tothe thirteenth embodiment is constituted by a fixed electrode portion 2d, a movable electrode portion 3 b and a circuit 71 connected to thefixed electrode portion 2 d and the movable electrode portion 3 b, asshown in FIG. 22. A detailed description will be made hereinafter.

As shown in FIG. 22, according to the thirteenth embodiment, a stopperfilm 42 made of a silicon nitride film is formed on a surface of a fixedelectrode 41 made of silicon in the fixed electrode portion 2 d. Thefixed electrode 41 is an example of the “second electrode” in thepresent invention. The stopper film 42 is an example of the “member” inthe present invention. The stopper film 42 is convexly formed on thesurface of the fixed electrode 41. The stopper film 42 is an example ofthe “projecting portion” in the present invention. As shown in FIG. 23,the stopper film 42 has oblong through holes in plan view. These throughholes and the surface of the fixed electrode 41 form the groove-shapedrecess portions 421. The recess portions 421 have widths W4 of about 10μm to about 1000 μm and depths D1 of about 0.1 μm to about 100 μm.According to the thirteenth embodiment, the interdigital electret film43, made of an organic material such as polytetrafluoroethylene (PTFE)or a silicon oxide film, having a thickness of about 0.1 μm to about 50μm is so formed as to be embedded in the bottom surfaces (surfaces,formed with no stopper film 42, of the fixed electrode 41) of thegroove-shaped recess portions 421. The stopper film 42 and the electretfilm 43 cover a surface, opposed to a movable electrode 62 describedlater, of the fixed electrode 41, and hence when charges are injectedfrom a side of the surface, opposed to the movable electrode 62, of thefixed electrode 41 by corona discharge, the charges to be injected canbe inhibited from flowing out through the fixed electrode 41 grounded(not shown). Consequently, dispersion of a surface potential of theelectret film 43 can be suppressed.

As shown in FIG. 22, the movable electrode portion 3 b is arranged at ainterval from the fixed electrode portion 2 d. In the movable electrodeportion 3 b, a movable electrode 62 made of aluminum, titanium or thelike is formed on a surface of a movable substrate 61 made of quartz.The movable electrode 62 is an example of the “first electrode” in thepresent invention. The movable electrode 62 is interdigitally formed asshown in FIG. 24.

As shown in FIG. 22, the fixed electrode 41 and the movable electrode 62are electrically connected to the circuit 71 through wires 72.

A power generating operation of the electrostatic induction powergenerating device 1 j according to the thirteenth embodiment of thepresent invention will be now described with reference to FIG. 22.

When no vibration is applied to the electrostatic induction powergenerating device 1 j, the stopper film 42 and the movable electrode 62are arranged to be opposed to each other at a prescribed interval, asshown in FIG. 22. Then, vibration is applied to the electrostaticinduction power generating device 1 j in a first direction of ahorizontal direction (direction X), so that the electret film 43 and themovable electrode 62 are arranged to be opposed to each other at aprescribed interval. At this time, positive charges or negative chargesare stored in the surface of the electret film 43, and charges oppositeto the charges stored in the electret film 43 on a side of the movableelectrode 62 are induced in the movable electrode 62 by electrostaticinduction.

Then, the electrostatic induction power generating device 1 j moves in asecond direction of the direction X, so that the stopper film 42 and themovable electrode 62 are opposed to each other as shown in FIG. 22.Thus, the amount of electric charges induced in the movable electrode 62is changed. This changed amount of the electric charges is extracted bythe circuit 71 connected to the fixed electrode 41 and the movableelectrode 62 thought the wires 72, thereby generating power.

According to the thirteenth embodiment, as hereinabove described, theelectrostatic induction power generating device 1 j comprises thestopper film 42 and the groove-shaped recess portions 421 provided onthe surface of the fixed electrode 41, and the electret film 43 is soformed as to be embedded in the bottom surfaces of the recess portions421, whereby the stopper film 42 can inhibit the movable electrode 62from moving in the direction Z (vertical direction) shown in FIG. 22 bya physical impact and coming into contact with the electret film 43, andhence the amount of electric charges stored in the electret film 43 canbe inhibited from change due to contact between the movable electrode 62and the electret film 43.

Fourteenth Embodiment

Referring to FIG. 25, a fixed electrode portion 2 e formed with aconductive layer 44 on a surface of a stopper film 42 will be describedin this fourteenth embodiment dissimilarly to the aforementionedthirteenth embodiment.

In this fixed electrode portion 2 e according to the fourteenthembodiment, the conductive layer 44 is formed on the surface of thestopper film 42, as shown in FIG. 25. The remaining structure of thefourteenth embodiment is similar to that of the aforementionedthirteenth embodiment.

According to the fourteenth embodiment, as hereinabove described, theconductive layer 44 is formed on the surface of the stopper film 42,whereby components other than a component in a direction perpendicularto a main surface of an electret film 43 in an electric field resultingfrom electric charges stored in the electret film 43 can be inhibitedfrom generation, and hence the electric field can be inhibited fromreaching a position not opposed to the main surface of the electret film43. Thus, difference in potentials between a position opposed to themain surface of the electret film 43 and the position not opposed to theelectret film 43 can be increased, and hence difference between theamount of electric charges induced in an movable electrode 62 (see FIG.22) by electrostatic induction in a case where the movable electrode 62is at the position opposed to the electret film 43 and the amount ofelectric charges induced in the movable electrode 62 by electrostaticinduction in a case where the movable electrode 62 is at the positionnot opposed to the electret film 43 can be increased. Consequently, theamount of power generation can be increased.

Fifteenth Embodiment

Referring to FIG. 26, a fixed electrode portion 2 f formed with grooveshaped recess portions 411 a and a projecting portion 412 a on a surfaceof a fixed electrode 41 a will be described in this fifteenth embodimentdissimilarly to the aforementioned thirteenth embodiment.

In this fixed electrode portion 2 f according to the fifteenthembodiment, the groove shaped recess portions 411 a and the projectingportion 412 a are formed on the surface of the fixed electrode 41 a, asshown in FIG. 26. The fixed electrode 41 a is an example of the “secondelectrode” in the present invention. Each of the recess portions 411 ahas a width W4 of about 10 μm to about 1000 μm and a depth D1 of about0.1 μm to about 100 μm. Similarly to the seventh embodiment shown inFIG. 23, the groove shaped recess portions 411 a are oblongly formed inplan view. According to the fifteenth embodiment, electret films 43 madeof an organic material such as PTFE or a silicon oxide film, having athickness of about 0.1 μm to about 50 μm smaller than the depth D1 ofeach recess portion 411 a is so formed as to fill up a bottom surface ofthe groove shaped recess portion 411 a.

The remaining structure of the fifteenth embodiment is similar to thatof the aforementioned thirteenth embodiment.

According to the fifteenth embodiment, as hereinabove described, thegroove shaped recess portions 411 a and the projecting portion 412 aprovided on the surface of the fixed electrode 41 a are provided and theelectret films 43 a are so formed as to be embedded in the bottomsurfaces of the recess portions 411 a, whereby the projecting portion412 a can inhibit a movable electrode 62 from moving in a direction Z(vertical direction) shown in FIG. 22 by a physical impact and cominginto contact with the electret films 43 a, and hence the amount ofelectric charges stored in the electret films 43 a can be inhibited fromchange due to contact between the movable electrode 62 and the electretfilms 43 a. Further, the electret films 43 a are so formed as to beembedded in the bottom surfaces of the recess portions 411 a provided onthe surface of the fixed electrode 41 a, whereby the electret films 43 aare not separated by cleavage in a case where a plurality of theelectret films 43 a are formed on the fixed electrode 41 a and the fixedelectrode 41 a is separated into individual fixed electrodes 41 a bycleavage, dissimilarly to a case where the electret film 43 a is formedon an overall surface of the fixed electrode 41 a, and hence charges canbe inhibited from flowing out of cleavage surfaces of the electret films43 a. Thus, reduction in surface potentials of the electret films 43 acan be suppressed.

Sixteenth Embodiment

Referring to FIG. 27, a fixed electrode portion 2 g where electret films43 b are formed also on side surfaces of groove shaped recess portions411 a will be described in this sixteenth embodiment dissimilarly to theaforementioned fifteenth embodiment.

In the fixed electrode portion 2 g according to the sixteenthembodiment, the electret films 43 b made of an organic material such asPTFE or a silicon oxide film are so formed as to be embedded in bottomsurfaces of the groove shaped recess portions 411 a and also in the sidesurfaces of the groove shaped recess portions 411 a as shown in FIG. 27.Thus, the electret films 43 b are formed on the side surfaces of thegroove shaped recess portions 411 a and a large number of electriccharges can be stored, and hence the amount of electric charges storedin the electret films 43 b can be increased. Consequently, the amount ofpower generation can be increased.

The remaining structure of the sixteenth embodiment is similar to thatof the aforementioned fifteenth embodiment.

Seventeenth Embodiment

Referring to FIG. 28, a fixed electrode portion 2 h where a stopper film45 a is formed on a surface of a projecting portion 412 a will bedescribed in this seventeenth embodiment dissimilarly to theaforementioned sixteenth embodiment.

In this fixed electrode portion 2 h according to the seventeenthembodiment, the stopper film 45 a made of an insulating film having abreakdown voltage smaller than electret films 43 b is formed on thesurface of the projecting portion 412 a, as shown in FIG. 28. Thestopper films 45 a are examples of the “member” in the presentinvention. While the electret films 45 b shown in FIG. 28 are formed oninner sides of groove shaped recess portions 411 a, the ends of theelectret films 45 b may be formed as to be embedded between the stopperfilm 45 a and the projecting portion 412 a. At this time, the ends ofthe stopper film 45 a is formed in upwardly warped shapes.

The remaining structure of the seventeenth embodiment are similar tothat of the aforementioned sixteenth embodiment.

According to the seventeenth embodiment, as hereinabove described, thestopper film 45 a having the breakdown voltage smaller than the electretfilms 43 b is formed on the surface of the projecting portion 412 a,whereby even when the electret films 43 b and the stopper film 45 a aresimultaneously made electret, the stopper film 45 a first causesdielectric breakdown due to the smaller breakdown voltage of the stopperfilm 45 a than the electret films 43 b, and hence the electret films 43b can store a larger number of electric charges and the amounts ofelectric charges stored in the electret films 43 b and the stopper film45 a are made different from each other. Thus, an intensity of anelectric field on the surface of each electret film 43 b and anintensity of an electric field on the surface of the stopper film 45 acan be made different. The stopper film 45 a is formed on the surface ofthe projecting portion 412 a, whereby the movable electrode 62 (see FIG.22) and the electret films 43 b can be easily inhibited from coming intocontact with each other.

Eighteenth Embodiment

Referring to FIG. 29, a fixed electrode portion 2 i formed with a chargeoutflow inhibition film 46 on a surface thereof will be described inthis eighteenth embodiment dissimilarly to the aforementionedseventeenth embodiment.

In this fixed electrode portion 2 i according to the eighteenthembodiment, the charge outflow inhibition film 46 made of MSQ (methylsilses quioxane) is formed on the surface of the fixed electrode portion2 i as shown in FIG. 29. Thus, electric charges can be inhibited fromflowing out of electret films 43 b. The electret films 43 b are formedon bottom surfaces and side surfaces of recess portions 411 a andcentral portions of the electret films 43 b are concave. The chargeoutflow inhibition film 46 formed on the central portions of theelectret films 43 b is also concave similarly to this. Thus, the chargeoutflow inhibition film 46 formed on the central portions of theelectret films 43 b can be inhibited from deterioration even when thecharge outflow inhibition film 46 formed on the stopper film 45 a isdeteriorated by abrasion or the like. Consequently, the life of theelectret films 43 b can be increased.

The remaining structure of the eighteenth embodiment is similar to thatof the aforementioned seventeenth embodiment.

Nineteenth Embodiment

Referring to FIG. 30, a fixed electrode portion 2 j where electret films43 c are formed also on side surfaces of a stopper film 45 a will bedescribed in this nineteenth embodiment dissimilarly to theaforementioned seventeenth embodiment.

In the fixed electrode portion 2 j according to the nineteenthembodiment, the electret films 43 c made of an organic material such asPTFE or a silicon oxide film are so formed as to be embedded in bottomsurfaces of groove shaped recess portions 411 a and also in sidesurfaces of the groove shaped recess portions 411 a and the sidesurfaces of the stopper film 45 a as shown in FIG. 30. The electretfilms 43 c are formed also on the side surfaces of the stopper film 45 aand electric charges stored in the electret films 43 c can be increased.

The remaining structure of the nineteenth embodiment is similar to thatof the aforementioned seventeenth embodiment.

Twentieth Embodiment

Referring to FIG. 31, a fixed electrode portion 2 k where electret films43 d are so formed as to be embedded in recess portions 411 a will bedescribed in this twentieth embodiment dissimilarly to theaforementioned nineteenth embodiment.

In this fixed electrode portion 2 k according to the twentiethembodiment, the electret films 43 d made of an organic material such asPTFE or a silicon oxide film are so formed as to be embedded in recessportions 411 a as shown in FIG. 31.

The remaining structure of the twentieth embodiment is similar to thatof the aforementioned seventeenth embodiment.

The effects of the twentieth embodiment are similar to those of theaforementioned seventeenth embodiment.

Twenty-First Embodiment

Referring to FIG. 32, a fixed electrode portion 21 where recess portions411 b are so formed that widths thereof are increased from bottomsurfaces of the recess portions 411 b toward open upper ends thereofwill be described in this twenty-first embodiment dissimilarly to theaforementioned fifteenth to twentieth embodiments.

In the fixed electrode portion 21 according to the twenty-firstembodiment, the groove shaped recess portions 411 b and a projectingportion 412 b are formed on a surface of a fixed electrode 41 b as shownin FIG. 32. The fixed electrode 41 b is an example of the “secondelectrode” in the present invention. The projecting portion 412 b is anexample of the “member” in the present invention. The recess portions411 b have widths W5 of about 10 μm to about 1000 μm and depths D3 ofabout 0.1 μm to about 100 μm. According to the twenty-first embodiment,the recess portions 411 b are so formed that the widths thereof areincreased from the bottom surfaces of the recess portions 411 b towardthe open upper ends thereof. The groove shaped recess portions 411 b areoblongly formed in plan view similarly to the thirteenth embodimentshown in FIG. 23. In the groove shaped recess portions 411 b, electretfilms 43 e made of an organic material such as PTFE of a silicon oxidefilm are formed on bottom surfaces of the recess portions 411 b withthicknesses D4 of about 0.1 μm to about 50 μm smaller than depths D3 ofthe recess portions 411 b.

The remaining structure of the twenty-first embodiment is similar tothat of the aforementioned thirteenth embodiment.

According to the twenty-first embodiment, as hereinabove described, therecess portions 411 b are so formed that the widths thereof areincreased from the bottom surfaces of the recess portions 411 b towardthe open upper ends thereof, whereby the thicknesses of the electretfilms 43 e in the vicinity of the side surfaces of the recess portions411 b are reduced, and hence electric fields in the vicinity of the sidesurfaces of the recess portions 411 b become weak. Thus, discharge fromthe electret films 43 e can be suppressed, when a movable electrode 62(see FIG. 22) comes close. The electric fields in the vicinity of theside surfaces of the recess portions 411 b are weak, and hence injectionof electric charges in the bottom surfaces of the electret films 43 ecan be inhibited from becoming difficult due to repulsion force of theelectric fields in the vicinity of the side surfaces of the recessportions 411 b when electric charges are injected in the electret films43 e by corona discharge. Further, the recess portions 411 b are soformed that the widths thereof are increased from the bottom surfaces ofthe recess portions 411 b toward the open upper ends thereof, wherebythe side surfaces of the recess portions 411 b are inclined and hencethe movable electrode 62 (see FIG. 22) can be inhibited from catchingthe side surfaces of the recess portions 411 b.

Twenty-Second Embodiment

Referring to FIG. 33, a fixed electrode portion 2 m where a stopper film45 b is formed on a surface of a projecting portion 412 b will bedescribed in this twenty-second embodiment dissimilarly to theaforementioned twenty-first embodiment.

In this fixed electrode portion 2 m according to the twenty-secondembodiment, the stopper film 45 b made of an insulating film, having abreakdown voltage smaller than electret films 43 e is formed on thesurface of the projecting portion 412 b, as shown in FIG. 33. Thestopper film 45 b is an example of the “member” in the presentinvention. The stopper film 45 b is formed on the surface of theprojecting portion 412 b, whereby contact between a movable electrode 62(see FIG. 22) and the electret films 43 e can be easily suppressed.

The remaining structure of the twenty-second embodiment is similar tothat of the aforementioned twenty-first embodiment.

Twenty-Third Embodiment

Referring to FIG. 34, a fixed electrode portion 2 n where electret films43 f are formed also on side surfaces of groove shaped recess portions411 b will be described in this twenty-third embodiment dissimilarly tothe aforementioned twenty-first embodiment.

In this fixed electrode portion 2 n according to the twenty-thirdembodiment, the electret films 43 f made of an organic material such asPTFE or a silicon oxide film are so formed as to be embedded in bottomsurfaces of the groove shaped recess portions 411 b and also in the sidesurfaces of the groove shaped recess portions 411 b as shown in FIG. 34.Thus, the electret films 43 f are formed also on the side surfaces ofthe groove shaped recess portions 411 b and can store a larger amountsof electric charges, and hence the amount of electric charges stored inthe electret films 43 f can be increased. Consequently, the amount ofpower generation can be increased.

The remaining structure of the twenty-third embodiment is similar tothat of the aforementioned twenty-first embodiment.

The effects of the twenty-third embodiment are similar to those of theaforementioned twenty-first embodiment.

Twenty-Fourth Embodiment

Referring to FIG. 35, a fixed electrode portion 2 o where a stopper film45 b is formed on a surface of a projecting portion 412 b will bedescribed in this twenty-fourth embodiment dissimilarly to theaforementioned twenty-third embodiment.

In this fixed electrode portion 2 o according to the twenty-fourthembodiment, the stopper film 45 b made of an insulating film having abreakdown voltage smaller than electret films 43 f is formed on thesurface of the projecting portion 412 b, as shown in FIG. 35. Thestopper films 45 b are examples of the “member” in the presentinvention.

The remaining structure of the twenty-fourth embodiment is similar tothat of the aforementioned twenty- third embodiment.

According to the twenty-fourth embodiment, as hereinabove described, thestopper film 45 b having the breakdown voltage smaller than the electretfilms 43 f is formed on the surface of the projecting portion 412 b,whereby even when the electret films 43 f and the stopper film 45 b aresimultaneously made electret, the stopper film 45 b first causesdielectric breakdown due to the smaller breakdown voltage of the stopperfilm 45 b than the electret films 43 f, and hence the amounts ofelectric charges stored in the electret films 43 f and the stopper film45 b can be made different from each other. Thus, an intensity of anelectric field on the surface of each electret film 43 f and anintensity of an electric field on the surface of the stopper film 45 bcan be made different.

Twenty-Fifth Embodiment

Referring to FIG. 36, a fixed electrode portion 2 p where a projectingportion 413 c is formed on ends of a fixed electrode 41 c will bedescribed in this twenty-fifth embodiment dissimilarly to theaforementioned fifteenth to twenty-fourth embodiments.

In this fixed electrode portion 2 p according to the twenty-fifthembodiment, groove shaped recess portions 411 c and a projecting portion412 c are formed on a surface of the fixed electrode 41 c made ofsilicon as shown in FIG. 36. The fixed electrode 41 c is an example ofthe “second electrode” in the present invention. Similarly to thethirteenth embodiment shown in FIG. 23, the groove shaped recessportions 411 c are oblongly formed in plan view. According to thetwenty-fifth embodiment, the projecting portion 413 c for inhibiting amovable electrode 62 (see FIG. 22) and electret films 43 g, describedlater, from coming into contact with each other is formed on the ends ofthe fixed electrode portion 2 p. The projecting portion 413 c is anexample of the “member” in the present invention. The electret films 43g made of an organic material such as PTFE or a silicon oxide film areso formed as to be embedded in bottom surfaces of the groove shapedrecess portions 411 c and cover the side surfaces of the recess portions411 c.

The remaining structure of the twenty-fifth embodiment is similar tothat of the aforementioned thirteenth embodiment.

According to the twenty-fifth embodiment, as hereinabove described, theprojecting portion 413 c for inhibiting the movable electrode 62 and theelectret films 43 g from coming into contact with each other isprovided, whereby the movable electrode 62 can be inhibited from movingin a direction Z (vertical direction) shown in FIG. 22 by a physicalimpact and coming into contact with the electret films 43 g, and hencethe amount of electric charges stored in the electret films 43 g can beinhibited from change due to contact between the movable electrode 62and the electret films 43 g.

Twenty-Sixth Embodiment

Referring to FIG. 37, a fixed electrode portion 2 q where a chargeoutflow inhibition film 48 is formed on surfaces of an electret film 43i and conductive layers 47 will be described in this twenty-sixthembodiment dissimilarly to the aforementioned twenty-fifth embodiment.

In this fixed electrode portion 2 q according to this twenty-sixthembodiment, a groove shaped recess portion 411 e and a projectingportion 412 e are formed on a surface of a fixed electrode 41 e made ofsilicon, quartz, plastic or Teflon (registered trademark) as shown inFIG. 37. The fixed electrode 41 e made of silicon is an example of the“second electrode” in the present invention. The groove shaped recessportion 411 e is rectangularly formed in plan view. The projectingportion 412 e has a function of inhibiting a movable electrode 62 (seeFIG. 22) and the electret film 43 i, described later, from coming intocontact with each other. The projecting portion 412 e is an example ofthe “member” in the present invention. The electret film 43 i made of anorganic material such as PTFE or a silicon oxide film, having athickness of about 0.1 μm to about 50 μm is so formed as to be embeddedin bottom surface of the groove shaped recess portion 411 e. Projectingportions 431 i are formed on a surface of the electret film 43 i on aside opposed to the movable electrode 62 (see FIG. 22). The conductivelayers 47 are formed on surfaces of the projecting portions 431 i. Thecharge outflow inhibition film 48 made of MSQ is formed on the surfacesof the projecting portions 431 i and the conductive layers 47. Thus,electric charges can be inhibited from flowing out of the surface of theelectret film 43 i.

The remaining structure of the twenty-sixth embodiment is similar tothat of the aforementioned thirteenth embodiment.

Twenty-Seventh Embodiment

Referring to FIG. 38, an electrostatic induction power generating device1 k where stopper films 93 are arranged between a movable substrate 92and a fixed electrode 90 will be described in this twenty-seventhembodiment dissimilarly to the aforementioned first to twenty-sixthembodiments.

In this electrostatic induction power generating device 1 k according tothe twenty-seventh embodiment, electret films 91 are formed on a surfaceof the fixed electrode 90 made of silicon as shown in FIG. 38. Movableelectrodes 93 are so formed on a surface of the movable substrate 92arranged to be opposed to the fixed electrode 90 as to be opposed to theelectret films 91. The movable electrodes 93 is an example of the “firstelectrode” in the present invention. The fixed electrode 90 is anexample of the “second electrode” in the present invention. The stopperfilms 94a re arranged between the fixed electrode 90 and the movablesubstrate 92 at intervals from the fixed electrode 90 and the movablesubstrate 92. Thus, the movable electrodes 93 and the electret films 91can be inhibited from coming into contact with each other. The stopperfilms 94 are examples of the “member” in the present invention.

In the electrostatic induction power generating device 1 k, the movablesubstrate 92 and the fixed electrode 90 relatively move in a directionX, whereby the amount of electric charges stored in the movableelectrodes 93 are changed by electrostatic induction resulting fromelectric charges stored in the electret films 91, and hence power can begenerated by extracting this changed amount of the electric charges.

Twenty-Eighth Embodiment

Referring to FIGS. 39 and 40, an electrostatic induction powergenerating device 1 l where stopper films 94 a are arranged on a housing95 will be described in this twenty-eighth embodiment dissimilarly tothe aforementioned twenty-seventh embodiment.

In this electrostatic induction power generating device 1 l according tothe twenty-eighth embodiment, a movable substrate 92 is formed on alower surface of inner surfaces of the housing 95, as shown in FIG. 39.Movable electrodes 93 are formed on a lower surface of the movablesubstrate 92. The movable electrodes 93 are examples of the “firstelectrode” in the present invention. The movable electrodes 93 areinterdigitally formed. The fixed electrode 90 made of silicon isarranged at an interval from the movable substrate 92. The fixedelectrode 90 is an example of the “second electrode” in the presentinvention. As shown in FIG. 40, the electret films 91 are formed on anupper surface of the fixed electrode 90 on a side of the movableelectrodes 93 and are oblongly formed similarly to the movableelectrodes 93.

As shown in FIG. 39, the stopper films 94 a are arranged on sidesurfaces of the inner surfaces of the housing 95 between the fixedelectrode 90 and the movable substrate 92 at intervals from the fixedelectrode 90 and the movable substrate 92. The stopper films 94 a areexamples of the “member” in the present invention. The stopper films 94a are formed in a direction parallel to an extensional direction of theoblong movable electrodes 93.

In the electrostatic induction power generating device 1 l, the movablesubstrate 92 (housing 95) and the fixed electrode 90 relatively move ina direction X, whereby the amount of electric charges stored in themovable electrodes 93 are changed by electrostatic induction resultingfrom electric charges stored in the electret films 91, and hence powercan be generated by extracting this changed amount of the electriccharges.

Twenty-Ninth Embodiment

Referring to FIG. 41, an electrostatic induction power generating device1 m where a fixed electrode 90 is fixed to a housing 95 will bedescribed in this twenty-ninth embodiment dissimilarly to theaforementioned twenty-eighth embodiment.

In this electrostatic induction power generating device 1 m according tothe twenty-ninth embodiment, the fixed electrode 90 is formed on anupper surface of an inner surface of the housing 95 as shown in FIG. 41.A movable substrate 92 is not fixed to the housing 95 dissimilarly tothe twenty-eighth embodiment. The remaining structure of thetwenty-ninth embodiment is similar to that of the aforementionedtwenty-eighth embodiment.

Thirtieth Embodiment

Referring to FIG. 42, an electrostatic induction power generating device1 n where stopper films 94 a are in contact with a fixed electrode 90and a movable substrate 92 will be described in this thirtiethembodiment dissimilarly to the aforementioned twenty-ninth embodiment.

In this electrostatic induction power generating device 1 n according tothe thirtieth embodiment, the stopper films 94 a are arranged in contactwith the fixed electrode 90 and the movable substrate 92 as shown inFIG. 42.

Thirty-First Embodiment

Referring to FIGS. 43 to 45, an electrostatic induction power generatingdevice 1 o where stopper films 94 a and a stopper film 94 b are arrangedon side surfaces and a central portion of inner surfaces of a housing 95respectively will be described in this thirty-first embodimentdissimilarly to the aforementioned thirtieth embodiment.

In this electrostatic induction power generating device 1 o

according to the thirty-first embodiment, the stopper films 94 a arearranged on the side surfaces of the inner surfaces of the housing 95and the stopper film 94 b is arranged on the central portion of theinner surfaces of the housing 95, as shown in FIGS. 43 to 45. Thus, theelectret films 91 and the movable electrodes 93 can be inhibited fromcoming into contact with each other at the central portion even when themovable substrate 92 and the fixed electrode 90 are warped. The stopperfilm 94 b is an example of the “member” in the present invention. Theelectret films 91 are oblongly formed and the stopper films 94 a and 94b are so formed as to extend in a direction Y intersecting with anextensional direction (direction X) of the oblong electret films 91. Inthe electrostatic induction power generating device 1 o, the movablesubstrate 92 and the fixed electrode 90 relatively move in the directionY, thereby generating power.

Thirty-Second Embodiment

Referring to FIGS. 46 and 47, an electrostatic induction powergenerating device 1 p where stopper films 94 a are arranged only on sidesurfaces of inner surfaces of a housing 95 will be described in thisthirty-second embodiment dissimilarly to the aforementioned thirty-firstembodiment.

In this electrostatic induction power generating device 1 p according tothe thirty-second embodiment, the stopper films 94 a are arranged on theside surfaces of the inner surfaces of the housing 95 as shown in FIGS.46 and 47 and not arranged on a central portion of the housing 95dissimilarly to the aforementioned thirty-first embodiment. Theremaining structure of the thirty-second embodiment is similar to thatof the aforementioned thirty-first embodiment.

Thirty-Third Embodiment

Referring to FIGS. 48 and 49, an electrostatic induction powergenerating device 1 q where stopper film 94 b is arranged only on acentral portion of inner surfaces of a housing 95 will be described inthis thirty-third embodiment dissimilarly to the aforementionedthirty-first embodiment.

In this electrostatic induction power generating device 1 q according tothe thirty-third embodiment, the stopper film 94 b is arranged on thecentral portion of the inner surfaces of the housing 95 as shown inFIGS. 48 and 49 and not arranged on the side surfaces of the housing 95dissimilarly to the aforementioned thirty-first embodiment. Theremaining structure of the thirty-third embodiment is similar to that ofthe aforementioned thirty-first embodiment.

Thirty-Fourth Embodiment

Referring to FIG. 50, an electrostatic induction power generating device1 r where stopper films 96 a are formed on a lower surface of a movableelectrode 92 will be described in this thirty-fourth embodimentdissimilarly to the aforementioned thirteenth embodiment.

In this electrostatic induction power generating device 1 r according tothe thirty-fourth embodiment, movable electrodes 93 are formed on thelower surface of the movable electrode 92 and the stopper films 96 a arearranged on ends of the movable substrate 92 to be adjacent to themovable electrodes 93, as shown in FIG. 50. The stopper films 96 a areexamples of the “member” in the present invention. A fixed electrodeportion 2 f is provided to be opposed to the movable substrate 92. Thestructure of the fixed electrode portion 2 f is similar to that of theaforementioned fifteenth embodiment shown in FIG. 26.

In this electrostatic induction power generating device 1 r, theprojecting portion 412 a protruding beyond surfaces of electret films 43a is provided on the fixed electrode portion 2 b and the stopper films96 a are arranged on the lower surface of the movable substrate 92,whereby the movable electrode 92 and the electret films 43 a can befurther inhibited from coming into contact with each other.

Thirty-Fifth Embodiment

Referring to FIG. 51, an electrostatic induction power generating device1 s where stopper films 96 b are arranged between a movable substrate 92and a fixed electrode portion 2 f will be described in this thirty-fifthembodiment dissimilarly to the aforementioned thirty-fourth embodiment.

In this electrostatic induction power generating device 1 s according tothe thirty-fifth embodiment, the stopper films 96 b are arranged betweenthe movable substrate 92 and the fixed electrode portion 2 f atintervals from the movable substrate 92 and the fixed electrode portion2 f, as shown in FIG. 51. The stopper films 96 b are examples of the“member” in the present invention. The stopper films 96 b are arrangedat positions opposed to ends of the movable substrate 92 and the fixedelectrode portion 2 f. The remaining structure of the thirty-fifthembodiment is similar to that of the aforementioned thirty-fourthembodiment.

Thirty-Sixth Embodiment

Referring to FIG. 52, an electrostatic induction power generating device1 t where stopper films 96 c are arranged on an upper surface of a fixedelectrode portion 2 f will be described in this thirty-sixth embodimentdissimilarly to the aforementioned thirty-fourth embodiment.

In this electrostatic induction power generating device 1 t according tothe thirty-sixth embodiment, the stopper films 96 c are arranged on theupper surface of ends of the fixed electrode portion 2 f, as shown inFIG. 52. The stopper films 96 c are examples of the “member” in thepresent invention. The remaining structure of the thirty-sixthembodiment is similar to that of the aforementioned thirty-fourthembodiment.

Thirty-Seventh Embodiment

Referring to FIG. 53, a movable electrode portion 3 c where a protectivefilm 97 covers a surface of a movable electrode portion 3 c will bedescribed in this thirty-seventh embodiment dissimilarly to theaforementioned first to thirty-sixth embodiments.

In this movable electrode portion 3 c according to the thirty-sixthembodiment, movable electrodes 93 are formed on a lower surface of amovable substrate 92 as shown in FIG. 53. The protective film 97 made ofan insulating film such as a silicon oxide film or a silicon nitridefilm is formed to cover the lower surface of the movable substrate 92and surfaces of the movable electrodes 93.

According to the thirty-seventh embodiment, as hereinabove described,the protective film 97 made of the insulating film such as the siliconoxide film or the silicon nitride film is formed to cover the lowersurface of the movable substrate 92 and the surfaces of the movableelectrodes 93, whereby the protective film 97 can inhibit electret filmsarranged on positions opposed to the movable electrodes 93 and themovable electrodes 93 from coming into contact with each other.

Thirty-Eighth Embodiment

Referring to FIG. 54, an electrostatic induction power generating device1 u where a movable electrode 62 and a movable electrode 62 a areprovided on a surface of a movable substrate 7 to be adjacent to eachother will be described in this thirty-eighth embodiment dissimilarly tothe aforementioned first to thirty-seventh embodiments.

As shown in FIG. 54, this electrostatic induction power generatingdevice 1 u according to the thirty-eighth embodiment is constituted by afixed electrode portion 2 r and a movable electrode portion 3 e. Adetailed description will be made hereinafter.

In the fixed electrode portion 2 r, an electret film 5 b made of athermal oxide film having projecting portions 501 a is formed on asurface of a fixed electrode 4 a made of silicon, as shown in FIG. 54.Conductive layers 6 b are formed on surfaces of the projecting portions501 a. The conductive layers 6 b are interdigitally or oblongly formed.A charge outflow inhibition film 48 a is formed to cover surfaces of theelectret film 5 b and the conductive layers 6 b. Stoppers 9 b are formedon ends of the electret film 5 b. Each of stoppers 9 b has a function asa spacer keeping an interval between the movable electrodes 62 and 62 aand the electret film 5 b constant.

In the movable electrode portion 3 e, the movable electrode 62 and themovable electrode 62 a are provided to be adjacent to each other on asurface of the movable substrate 7 made of quartz as shown in FIG. 54.The movable electrode 62 and the movable electrode 62 a are examples ofthe “first electrode” and the “second electrode” in the presentinvention respectively. A protective film 63 made of a sputtered oxidefilm or nitride film is formed to cover surfaces of the movablesubstrate 7, the movable electrode 62 and the movable electrode 62 a. Acircuit 71 is electrically connected to the movable electrode 62 and themovable electrode 62 a through wires 72.

A power generating operation of the electrostatic induction powergenerating device 1 u according to the thirty-eighth embodiment of thepresent invention will be now described with reference to FIG. 54.

When no vibration is applied to the electrostatic induction powergenerating device 1 u, the projecting portions 501 a of the electretfilm 5 b and the movable electrode 62 are arranged to be opposed to eachother at a prescribed interval, as shown in FIG. 54. At this time,positive electric charges or negative electric charges are stored in thesurface of the electret film 5 b. The conductive layers 6 b are formedon the surfaces of the projecting portions 501 a, whereby an electricfield on a surface of a recess portion 501 b which is a region formedwith no projecting portions 501 a on the surface of the electret film 5b is stronger than an electric field on the surfaces of the projectingportions 501 a. Consequently, electric charges electrostatically inducedin the movable electrode 62 a are larger than electric chargeselectrostatically induced in the movable electrode 62.

Then, the movable electrode 62 moves to a position opposed to the recessportion 501 b and the movable electrode 62 a moves to positions opposedto the projecting portions 501 a by application of horizontal vibration(in a direction X) to the electrostatic induction power generatingdevice 1 u and relative movement of the movable electrode portion 3 eand the fixed electrode portion 2 r in the direction X. Thus, electriccharges electrostatically induced in the movable electrodes 62 and 62 aare changed. This changed amount of the electric chargeselectrostatically induced in the movable electrodes 62 and 62 a isextracted as a current through the wires 72 by the circuit 71, wherebythe electrostatic induction power generating device 1 u can generatepower.

According to the thirty-eighth embodiment, as hereinabove described, theelectrostatic induction power generating device 1 u comprises thestoppers 9 b inhibiting the movable electrodes 62 and 62 a and theelectret film 5 b from coming into contact with each other, whereby themovable electrodes 62 and 62 a and the electret film 5 b can beinhibited from coming into contact with each other due to a physicalimpact, and hence the amount of electric charges stored in the electretfilm 5 b can be inhibited from change due to contact between the movableelectrodes 62 and 62 a and the electret film 5 b.

Thirty-Ninth Embodiment

Referring to FIG. 55, an electrostatic induction power generating device1 v where a projecting portion 401 c is formed on ends of a fixedsubstrate 4 b will be described in this thirty-ninth embodimentdissimilarly to the aforementioned thirty-eighth embodiment.

This electrostatic induction power generating device 1 v according tothe thirty-ninth embodiment is constituted by a fixed electrode portion2 s and a movable electrode portion 3 e as shown in FIG. 55. A detaileddescription will be made hereinafter.

In the fixed electrode portion 2 s, an electret film 5 b is so formed asto be embedded in a bottom surface of a recess portion 401 d of thefixed substrate 4 b made of silicon having the projecting portion 401 cand the recess portion 401 d, as shown in FIG. 55. The fixed substrate 4b is an example of the “substrate” in the present invention. Theprojecting portion 401 c is an example of the “member” in the presentinvention. The projecting portion 401 c has a function as a stopperinhibiting the movable electrodes 62 and 62 a and the electret film 5 bfrom coming into contact with each other and also has a function as aspacer keeping an interval between the movable electrodes 62 and 62 aand the electret film 5 b constant.

The remaining structure of the thirty-ninth embodiment is similar tothat of the aforementioned thirty-eighth embodiment.

An operation of the thirty-ninth embodiment is similar to that of theaforementioned thirty-eighth embodiment.

According to the thirty-ninth embodiment, as hereinabove described, theprojecting portion 401 c of the fixed substrate 4 b form a stopper toinhibit the movable electrodes 62 and 62 a and the electret film 5 bfrom coming into contact with each other, whereby the movable electrodes62 and 62 a and the electret film 5 b can be inhibited from coming intocontact with each other due to a physical impact, and hence the amountof electric charges stored in the electret film 5 b can be inhibitedfrom change due to contact between the movable electrodes 62 and 62 aand the electret film 5 b.

Fortieth Embodiment

Referring to FIG. 56, an electrostatic induction power generating device1 w where stoppers 9 b are formed on a surface of a protective film 63will be described in this fortieth embodiment dissimilarly to theaforementioned thirty-eighth embodiment.

In this electrostatic induction power generating device 1 w according tothe fortieth embodiment, the stoppers 9 b are formed on the surface ofthe protective film 63 as shown in FIG. 56. The remaining structure ofthe fortieth embodiment is similar to that of the aforementionedthirty-eighth embodiment.

An operation of the fortieth embodiment is similar to that of theaforementioned thirty-eighth embodiment.

Forty-First Embodiment

Referring to FIG. 57, an electrostatic induction power generating device1 x where insulating films 410 are formed on a surface of an electretfilm 5 a will be described in this forty-first embodiment dissimilarlyto the aforementioned thirty-eighth embodiment.

In a fixed electrode portion 2 t of this electrostatic induction powergenerating device 1 x according to the forty-first embodiment, theelectret film 5 a is formed on a surface of a fixed electrode 4 a asshown in FIG. 57. The insulating films 410 are formed on the surface ofthe electret film 5 a. The insulating films 410 are interdigitally oroblongly formed. Conductive layers 6 b are formed on surfaces of theinsulating films 410. A charge outflow inhibition film 48 a is formed tocover surfaces of the electret film 5 a and the conductive layers 6 b.

The remaining structure of the forty-first embodiment is similar to thatof the aforementioned thirty-eighth embodiment.

An operation of the forty-first embodiment is similar to that of theaforementioned thirty-eighth embodiment.

The embodiments disclosed this time must be considered as illustrativein all points and not restrictive. The range of the present invention isshown not by the above description of the embodiments but by the scopeof claims for patent, and all modifications within the meaning and rangeequivalent to the scope of claims for patent are included.

For example, while the example of employing the interdigital or oblongelectret film(s) and movable electrode(s) is shown in each of theaforementioned first to eleventh embodiments and thirteenth embodimentto forty-first embodiments, the present invention is not restricted tothis but a movable electrode(s) and an electret film(s) formed in shapesother than the interdigital shapes may be employed so far as the movableelectrode(s) and the electret film(s) are formed such that the opposingareas are changed by vibration.

While the example of employing the interdigital electret film andmovable electrode is shown in the aforementioned twelfth embodiment, thepresent invention is not restricted to this but a movable electrode(s)and an electret film(s) formed in shapes other than the interdigitalshapes may be employed so far as the movable electrode(s) and theelectret film(s) are opposed to each other.

While the example of employing the fixed substrate and the movablesubstrate made of glass is shown in each of the aforementioned seventhto twelfth embodiments, the present invention is not restricted to thisbut a fixed substrate and a movable substrate made of silicon may beemployed.

While the example of employing the column portion made of silicon isshown in each of the aforementioned seventh to twelfth embodiments, thepresent invention is not restricted to this but a column portion made ofpolyimide which is an organic polymer material may be employed.

While the example of employing the electret film made of Teflon(registered trademark) is shown in each of the aforementioned seventh totwelfth embodiments, the present invention is not restricted to this butan electret film made of PP (polypropylene), PET (polyethyleneterephthalate), PVC (polyvinyl chloride), PS (polystyrene), PTFE(polytetrafluoroethylene), PFA (copolymer of tetrafluoroethylene andperfluoro alkylvinyl ether), FEP (copolymer of tetrafluoroethylene andhexafluoropropylene), ETFE (copolymer of tetrafluoroethylene andethylene), PVDF (polyvinylidene-fluoride (2 fluoride)), PCTFE(polychlorotrifluoroethylene (3 fluoride)), ECTFE (ethylene-chlorotrifluoro ethylene copolymer), PVF (poly vinyl fluoride (polyvinylchloride)), SiO₂ (silicon oxide film), SiN (silicon nitride film) may beemployed.

While the example of forming the stopper film to be stacked on the guardelectrode is shown in each of the aforementioned eighth to eleventhembodiments, the present invention is not restricted to this but thestopper film and the guard electrode may be arranged on planarlydifferent positions.

While the example of forming the electret film on the side of the fixedelectrode is shown in each of the aforementioned seventh to twelfthembodiments, the present invention is not restricted to this but theelectret film may be formed on the side of the movable electrode.

While the example of forming the stopper film on the side of the fixedelectrode is shown in each of the aforementioned seventh to twelfthembodiments, the present invention is not restricted to this but thestopper film may be formed on the side of the movable electrode. Whenthe electret film and the stopper film are formed on different electrodesides, the electret film is deteriorated by contact between the electretfilm and the stopper film, and hence the electret film and the stopperfilm are preferably formed on the same electrode side.

While the example of forming the stopper film is shown in each of theaforementioned seventh to twelfth embodiments, the present invention isnot restricted to this but the guard electrode may be employed as astopper.

While the example where the ends of the projecting portion 412 a areangular is shown in the aforementioned fifteenth embodiment, the presentinvention is not restricted to this but ends of a projecting portion 412f of a fixed electrode 41 f having recess portions 411 f may bechamfered as in an fixed electrode portion 2 a shown in FIG. 58. Thus,the movable electrode 62 (see FIG. 22) can be inhibited from catchingthe projecting portion 412 f.

While the example where the surface of the movable substrate 7 is flatis shown in the aforementioned first embodiment, the present inventionis not restricted to this but recess portions 611 a may be formed on asurface of a movable substrate 61 a on a side opposed to a fixedelectrode portion 2 as in a movable electrode portion 3 f of anelectrostatic induction power generating device 120 shown in FIG. 59.Thus, projecting portions 412 d of a fixed electrode 41 d come intocontact with side surfaces of the recess portions 611 a of the movablesubstrate 61 a when the movable substrate 61 a vibrates in a directionX, and hence a vibration width of the movable substrate 61 a can beadjusted by adjusting widths of the recess portions 611 a.

While the example where the surface of the movable substrate 7 is flatis shown in the aforementioned first embodiment, the present inventionis not restricted to this but stopper portions 64 made of an insulatingfilm may be provided on a surface of a movable substrate 61 on a sideopposed to a fixed electrode portion 2 so as to hold upper ends ofprojecting portions 412 d of a fixed electrode 41 d therebetween as in amovable electrode portion 3 g of an electrostatic induction powergenerating device 121 shown in FIG. 60. Thus, the projecting portions412 d of the fixed electrode 41 d and the side surfaces of the stopperportions 64 come into contact with each other when the movable substrate61 vibrates in a direction X, and hence a vibration width of the movablesubstrate 61 can be adjusted by adjusting intervals of the stopperportions 64.

While the example of providing the projecting portion 401 b on thesurface of the fixed electrode 2 is shown in the aforementioned firstembodiment, the present invention is not restricted to this but a recessportion 611 b and projecting portions 612 b for inhibiting a movableelectrode 62 and conductive layers 47 from coming into contact with eachother may be provided on a surface of a movable substrate 61 b as in amovable electrode portion 3 h of an electrostatic induction powergenerating device 122 shown in FIG. 61 in place of provision of aprojecting portion on a surface of the fixed electrode 41 e of a fixedelectrode portion 2 v. At this time, the movable electrode 62 is formedon the surface of the recess portion 611 b.

While the example where the movable electrode portion 3 vibrates in thedirection X is shown in the aforementioned first embodiment, the presentinvention is not restricted to this but recess portions 611 c may beprovided on a surface, opposed to a fixed electrode portion 2, of amovable substrate 61 c as in a movable electrode portion 3 i of anelectrostatic induction power generating device 123 shown in FIG. 62,and a movable electrode portion 3 i may be vibrated in a direction Y(perpendicular to the plane of paper) perpendicular to the direction Xby moving projecting portions 412 d of the fixed electrode 41 d alongthe recess portions 611c.

While the example of forming the protective film 63 on the surfaces ofthe movable substrate 7, the movable electrode 62 and the movableelectrode 62 a is shown in the aforementioned thirty-eighth, the presentinvention is not restricted to this but no protective film 63 may beformed as in an electrostatic induction power generating device 124shown in FIG. 63. For example, a movable electrode portion 2 f may beemployed in a place of an electrode portion 2 r.

While the example of forming the stopper film 45 a on the surface of theprojecting portion 412 a of the fixed electrode 41 a is shown in theaforementioned seventeenth embodiment, the present invention is notrestricted to this but a conductive layer 50 may be formed as in a fixedelectrode portion 2 w shown in FIG. 64. Thus, an electric fieldresulting from electric charges stored in electret films 43 b formed tocover bottom surfaces of recess portions 411 a of the fixed electrode 41a can be inhibited from reaching positions not opposed to main surfacesof the electret films 43 b.

While the example of forming the electret film on the surface of thefixed electrode is shown in each of the aforementioned seventh totwelfth embodiments, the present invention is not restricted to this butthe electret film may be formed on a surface of a fixed substrate madeof silicon as shown in FIG. 65.

While the electrostatic induction power generating device shown in eachof the aforementioned first to forty-first embodiments may be applicablefor a wrist watch, a thermometer, a temperature indicator, a passometer,a remote control, a portable audio player, a keyless entry, a hearingaid, a pacemaker, a laser pointer, an electric toothbrush, a sensor, ane-book, a cell-phone, a digital camera, a game console, a refrigerator,a washing machine, a dish dryer and a tire pressure sensor, for example.

While the example of applying each of the aforementioned first toforty-first embodiments of the present invention to the electrostaticinduction power generating device as an electrostatic operation device,the present invention is not restricted to this but is also applicableto an electrostatic induction actuator, for example, other than theelectrostatic induction power generating device.

1. An electrostatic operation device comprising: a first electrode (8, 8a, 24, 24 a, 62, 93); an electret film (5, 5 a, 13, 43, 43 a to 43 i,91) so formed as to be opposed to said first electrode at an intervaltherebetween; and a member (9, 9 a, 14, 14 a to 14 c, 42, 94, 94 a, 94b, 96 a to 96 c, 401 b, 412 a to 412 f, 413 c, 612 d) inhibiting saidfirst electrode and said electret film from moving close to each otherwithin a prescribed interval.
 2. The electrostatic operation deviceaccording to claim 1, further comprising a second electrode (4, 4 a, 12,41, 41 a to 41 f, 90) so provided as to be opposed to said firstelectrode at an interval therebetween.
 3. The electrostatic operationdevice according to claim 2, wherein an end of a surface of said memberon a side of one of said first electrode and said second electrode ischamfered.
 4. The electrostatic operation device according to claim 2,further comprising a first substrate (21, 21 b) formed with said firstelectrode and a second substrate (11) formed with said second electrode,wherein said member is formed on a surface of one of said firstsubstrate and said second substrate.
 5. The electrostatic operationdevice according to claim 2, further comprising a first substrate (92)formed with said first electrode, wherein said member is provided on aposition between said first substrate and said second electrode atintervals from said first substrate and said second electrode.
 6. Theelectrostatic operation device according to claim 2, further comprisinga protective film (97) formed to cover a surface not formed with saidelectret film in the surfaces of said first and second electrodes. 7.The electrostatic operation device according to claim 1, wherein saidmember has a function as a stopper inhibiting said first electrode andsaid electret film from coming into contact with each other or a spacerkeeping an interval between said first electrode and said electret filmconstant.
 8. The electrostatic operation device according to claim 1,further comprising a guard electrode (15, 15 a) for inhibiting acomponent other than a component in a direction perpendicular to a mainsurface of said electret film in an electric field resulting fromelectric charges stored in said electret film from generation, providedto be adjacent to said electret film.
 9. The electrostatic operationdevice according to claim 8, further comprising a second electrode soprovided as to be opposed to said first electrode at an intervaltherebetween, wherein said member is so formed as to be stacked on asurface of said guard electrode on a side of one of said first electrodeand said second electrode.
 10. The electrostatic operation deviceaccording to claim 1, wherein said member inhibiting said firstelectrode and said electret film from moving close to each other withinthe prescribed interval functions as a guard electrode for inhibiting acomponent other than a component in a direction perpendicular to a mainsurface of said electret film in an electric field resulting fromelectric charges stored in said electret film from generation, providedto be adjacent to said electret film.
 11. The electrostatic operationdevice according to claim 1, further comprising a first substrate (21 a)formed with said first electrode, wherein said first electrode isembedded in said first substrate.
 12. The electrostatic operation deviceaccording to claim 1, wherein said member is formed between saidelectret film and said first electrode.
 13. The electrostatic operationdevice according to claim 1, further comprising a first substrate formedwith said first electrode, wherein said first substrate is supported bysaid member to be able to vibrate.
 14. The electrostatic operationdevice according to claim 1, further comprising a second substrate (90)formed with said electret film, wherein said second substrate issupported by said member to be able to vibrate.
 15. The electrostaticoperation device according to claim 1, further comprising a grooveshaped recess portion (401 a, 411 a to 411 f, 421) and a projectingportion (401 b, 412 a to 412 f) provided on a surface of one of saidfirst electrode and said second electrode, wherein said electret film isso formed as to be embedded in at least a bottom surface of said recessportion.
 16. The electrostatic operation device according to claim 15,wherein said groove shaped recess portion is so formed that a width isincreased from a bottom surface of said recess portion toward an openupper end thereof.
 17. The electrostatic operation device according toclaim 15, wherein a conductive layer is formed on a surface of saidprojecting portion.
 18. The electrostatic operation device according toclaim 15, wherein an insulating film (45 a, 45 b) having a smallerbreakdown voltage than said electret film is formed on a surface of saidprojecting portion.
 19. The electrostatic operation device according toclaim 15, wherein said electret film is formed on the bottom surface ofsaid recess portion to have a thickness smaller than a depth of saidrecess portion.
 20. The electrostatic operation device according toclaim 15, wherein an end of a surface of said projecting portion on aside of one of said first electrode and said second electrode is formedin a rounded shape or a chamfered shape.
 21. The electrostatic operationdevice according to claim 15, wherein a charge outflow inhibition film(46, 48) is formed on a surface of said electret film.
 22. Theelectrostatic operation device according to claim 15, wherein saidelectret film formed to be embedded in said groove shaped recess portionis oblongly formed in plan view.
 23. The electrostatic operation deviceaccording to claim 1, wherein said member is formed on a surface of saidelectret film.
 24. The electrostatic operation device according to claim23, wherein at least a part of said member is formed by a member softerthan said electret film.
 25. The electrostatic operation deviceaccording to claim 23, further comprising a conductive layer (10) formedon a surface of said member.
 26. The electrostatic operation deviceaccording to claim 23, wherein said member is so formed that a width isreduced toward a side on which said electret film is not formed.
 27. Anelectrostatic operation device comprising: a first electrode (62); asecond electrode (62 a) provided to be adjacent to said first electrodeat an interval therebetween; an electret film (5 b) formed to be opposedto said first electrode and said second electrode; and a member (9 b)having a function as a stopper inhibiting said first and secondelectrodes and said electret film from coming into contact with eachother or a spacer keeping an interval between said first and secondelectrodes and said electret film constant, between said first andsecond electrodes and said electret film.
 28. An electrostatic operationdevice comprising: a first electrode (62); a second electrode (62 a)provided to be adjacent to said first electrode at an intervaltherebetween; a substrate (4 b) to be opposed to said first electrodeand said second electrode and provided with a projecting portion (401 c)and a recess portion (401 d); and an electret film (5 b) formed to beembedded in a bottom surface of said recess portion provided on saidsubstrate, wherein said projecting portion provided on said substratehas a function as a stopper inhibiting said first and second electrodesand said electret film from coming into contact with each other or aspacer keeping an interval between said first and second electrodes andsaid electret film constant.